HOW TO HEAR VISUAL DISPARITIES - REAL-TIME STEREOSCOPIC SPATIAL DEPTHANALYSIS USING TEMPORAL RESONANCE

In a stereoscopic system, both eyes or cameras have a slightly differe nt view. As a consequence, small variations between the projected imag es exist ('disparities') which are spatially evaluated in order to ret rieve depth information (Sanger 1988; Fleet et al. 1991). A strong sim ilarity exists between the analysis of visual disparities and the dete rmination of the azimuth of a sound source (Wagner and Frost 1993). Th e direction of the sound is thereby determined from the temporal delay between the left and right ear signals (Konishi and Sullivan 1986). S imilarly, here we transpose the spatially defined problem of disparity analysis into the temporal domain and utilize two resonators implemen ted in the form of causal (electronic) filters to determine the dispar ity as local temporal phase differences between the left and right fil ter responses. This approach permits real-time analysis and can be sol ved analytically for a step function contrast change, which is an impo rtant case in all real-world applications. The proposed theoretical fr amework for spatial depth retrieval directly utilizes a temporal algor ithm borrowed from auditory signal analysis. Thus, the suggested simil arity between the visual and the auditory system in the brain (Wagner and Frost 1993) finds its analogy here at the algorithmical level. We will compare the results from the temporal resonance algorithm with th ose obtained from several other techniques like crosscorrelation or sp atial phase-based disparity estimation showing that the novel algorith m achieves performances similar to the 'classical' approaches using mu ch lower computational resources.